A determination method and an evaluation circuit are known, for example, from U.S. Pat. No. 4,249,223. The evaluation circuit is used in electromagnetic switching devices, in particular in contactors and isolating switches, in order to quench arcs that occur during opening of the contact.
U.S. Pat. No. 4,777,479 discloses a determination method for a switching state of a contact, via which an input voltage which is applied to an input of the contact can be passed on via a moving switching piece to an output of the contact, or can be disconnected from it. In this case, the method determines whether the input voltage is or is not being passed on to the output. The recorded nominal state is indicated.
The prior, not previously published, DE 100 25 276.1, describes a method for determining the switching state of a contact, via which an input voltage which is applied to an input of the contact can be passed on via a moving switching piece to an output of the contact, or can be disconnected from it. In this case as well, a contact voltage which is dropped between the input and the output is recorded, and the recorded contact voltage is used to determine whether the input voltage has or has not been disconnected from the input.